Re: Hi, I'm an engineer, tell me about your sunroof

I just bought my '08 acouple weeks ago. I drove one with a sun roof and didn't notice the noise referenced in this post. I opted for one without the sunroof because I didn't like what it did to the head room, particularly in the back seat. After reading this thread, I'm even more pleased with my decision to find one without the sunroof.

However, I have an idea for some that are having issues with squeaks. On my 2000 Camaro SS with T-tops, I put a little dielectric grease on the seals about once a year to keep them soft and prevent squeaks. This works wonders with the door seals, trunk seals, hatch seals etc as well. Spead the grease on liberally, wait about 20 minutes and wipe off the excess. This may not work on the sunroof on the CTS, since I don't have a sunroof, I don't know what the seals look like.

Re: Hi, I'm an engineer, tell me about your sunroof

Page 11-14 there's a table listing fluids/lubricants and it genericly references weatherstrip conditioning. It doesn't specificly say sunroof, but it does apply and it does mention Weatherstrip Lubricant (GM Part No. 3634770, in Canada 10953518) or Dielectric Silicone Grease (GM Part No. 12345579, in Canada 992887).

Re: Hi, I'm an engineer, tell me about your sunroof

My 2008 CTS sunroof has been leaking into the right rear floor under the seat and into the trunk. I pulled the headliner down enough to see the drain tube (green tube in the picture) on the right rear. Question is what is the small white tube in the picture? It shouldn't be loose, where does it go and what does it do?

Re: Hi, I'm an engineer, tell me about your sunroof

It's attached to the sunroof module further in. The tube provides a route for excess length of the cables which drive the sunroof and sunshade when they travel. The tube keeps them from rubbing against other things which would create a noise.

Your drain hose connection there looks good, more likely it's loose where it goes into the wheel well - particularly if you aren't seeing the headliner getting wet.

Re: Hi, I'm an engineer, tell me about your sunroof

Thanks for you quick response. No, it's connected in the trunk, see post #90 above. I have the mat out of the trunk and the side curtains on both sides pulled back. Water is running down the right rear pillar into the trunk and down behind the seat back and into the floor under the seat. I observed this before I pulled the headliner down.
When I first pulled the headliner down, on the right rear enough to see above, there was water present. Now that I have the headliner down on both sides enough to see I have yet to run water over the roof and try to determine where it is coming from (have to wait for help). Question, how much can the sunroof seals leak without causing a problem? My seals look good but do not seal completely water tight as I explained in post #90. Help would be appreciated.

Re: Hi, I'm an engineer, tell me about your sunroof

My recommendation would be to replace the center water channel. On the sides, there is a water channel in the aluminum side rail. Usually, there is evidence of where the water has been flowing by way of the dirt deposited from the rain water. If you see that the rain flowing out of the center water channel is hitting the aluminum side rails of the sunroof module outside of the water channel where it is intended to go, that could mean the water coming out of the center water channel is overshooting. A new part may resolve the situation.

If you don't see that, then it's possible that the seal between the aluminum side frame and the plastic end piece where the drain hose connects is leaking. Dealerships try to fix this with RTV to varying degrees of success... It's not a repair that always works, and when you can't reseal that joint the other repair is replacement of the frame.

Are you out of warranty? Replacement frames are expensive. The center water channel is a lot less expensive.

Re: Hi, I'm an engineer, tell me about your sunroof

Thanks WillK for your reply. I don't know about the warranty, I bought the car a few weeks ago. It is a 2008 with 66,000 miles and is in perfect condition except for the leak.
What is the procedure for changing the center channel? Does the headliner have to come all the way out? Thanks for the help.

Re: Hi, I'm an engineer, tell me about your sunroof

I believe the factory warranty is 50k miles.

I think the center channel can be changed without removing the headliner and module, but you might need to remove the front glass panel. I'll see if I can find a procedure, but someone like Rippy might have an easier time finding that.

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Actually I found it, and it doesn't require removal of the glass.

Sunroof Water Gutter Housing Drain Screw (Qty: 2)

Caution: Refer to Fastener Caution .

Procedure

1. Push downward on the sunroof panel side opening cover to view the sunroof water gutter housing drain screws.

2. After removing the screws, push outward on each rear corner of the gutter to release it from the side tracks.

Re: Hi, I'm an engineer, tell me about your sunroof

Thanks, that's good news about the center gutter. I will check it out more on Saturday. I believe you're right about the warranty, looks like 4 years 5000 miles/ 5 years 100,000 miles powertrain. Thanks again for the procedure and part numbers for the center gutter.

Re: Hi, I'm an engineer, tell me about your sunroof

My 08 was purchased last summer. I was in for several warranty issues and noticed how quiet my loaner CTS was. One with and one without the sunroof.

My sunroof was whooshing at speeds of 40+. Pushing up on the center bar helped some. The center bar was warped and the seal was not contacting the roof in the center. Adding a 3/16 thick home depot foam weatherstrip to the top of both center bar seals helped a lot. Replacement of the center bar helped some. It is plastic (IIRC) and may have warped from the sun. Curvature is improved, but still not perfect curve shape and still not quiet.

Obtained service manuals and it mentioned an adjustment procedure. Glass to be flush or 1mm lower than roof. Perimeter seals to grab a feeler guage (.020" IIRC?) Tested. Permimeter seal between 2 glasses had an air gap in several places, up to .020"., and so did rear of glass to body. So obviously just moving rear glass forward or backward wasn't going to help. The factory seal appeared to have shrunk due to age (4 years) and possible weather exposure; car was based in Miami part of its life. Perimeter seal looked dried and not springy. Poly window edge piece has small cracking. Perimeter seal appears to be the primary wind&water seal, and is very small, only 4mm vertically and horizontally. Very little compression even where it was not leaking and had visible air gap in several locations. Applied blue painters tape to rear of glass to body seal, area of worst offender. Silent. Took it to dealer that way and he replaced rear glass perimeter seal, but not the front one. Much better but still not as quiet as it was with the masking tape. Replacement seal protrudes upward almost 1mm from glass in a couple spots.

B to B warranty is gone now, so I guess I'll be fixing it myself come better weather. Guess I'll try a new front perimeter seal and careful adjustment. The one 2012 I drove was stone quiet. Not this one. Have seriously considered considered RTVing the rear glass in place.

Re: Hi, I'm an engineer, tell me about your sunroof

Originally Posted by leigh1322

B to B warranty is gone now, so I guess I'll be fixing it myself come better weather. Guess I'll try a new front perimeter seal and careful adjustment. The one 2012 I drove was stone quiet. Not this one. Have seriously considered considered RTVing the rear glass in place.

So, the rear glass panel has the perimeter seal in basicly a U shape while the front glass panel has the seal all the way around the panel, the back edge contacts the polyurethane encapsulation of the glass panel directly. There was initially an issue on some vehicles where the rear glass seal could be sticking out causing some wear at the corners of the front glass and there was a TSB for that.

Assuming your rear seal was replaced since you acquired your car last summer, it probably reflects the latest seal as of what is available today. There's a good chance that if you get the front seal you'd get a part that has been improved upon since the time the seal you have on your vehicle was produced.

Re: Hi, I'm an engineer, tell me about your sunroof

Re: see posts 90, 95, 97 & 101. When I checked the rear drain hoses, both the right and left were pinched almost flat in several places. It looked like the wiring harness and drain hoses were trying to occupy the same space in several places causing the drain hoses to become pinched. The hoses were draining but maybe too slow. I hope this is what was causing the sunroof trough to overflow.
Since I have the headliner down, I ordered new right and left drain hoses, a new center gutter/seals and for good measure a new front roof panel seal. Parts came today! I will be installing these parts when time allows and will check for leaks before re-installing the headliner.
Question: Has anyone installed the front roof panel seal? Can it be done without removing the roof panel? Does it just get stuffed in a groove around the perimeter? Does it get glue?

Re: Hi, I'm an engineer, tell me about your sunroof

Real quick.. the glass seal is retained by a groove on the polyurethane encapsulating the glass panel. No glue involved.

I'll see if I can dig up the procedure, but it will probably involve removing the glass panel (just a guess). I've seen it done without removing the panel though.

If you have the headliner down, you could probably drop the module, change the seal then bolt the module back in and not have to re-adjust the glass. I guess try getting the seal on with the module installed first, but if you find you keep popping the seal off part way around you could then try taking out the module.

To install the seal with the module in the vehicle, you'll have to go around the back edge with the glass in vent, then close the sunroof and go into partially open position to get the front edge.

I think that the way to do it is attach at the center then work your way out. Part of the trick is getting all the seal on without coming up short or having a bunch of excess length gathered into one spot.